Marijuana (Cannabis sativa L.) and its derivatives have been used for centuries for medicinal and recreational purposes. A major active ingredient in marijuana and hashish has been determined to be Δ9-tetrahydrocannabinol (Δ9-THC). Detailed research has revealed that the biological action of Δ9-THC and other members of the cannabinoid family occurs through two G-protein coupled receptors termed CB1 and CB2. The CB1 receptor is primarily found in the central and peripheral nervous systems and to a lesser extent in several peripheral organs. The CB2 receptor is found primarily in lymphoid tissues and cells. Three endogenous ligands for the cannabinoid receptors derived from arachidonic acid have been identified (anandamide, 2-arachidonoyl glycerol, and 2-arachidonyl glycerol ether). Each is an agonist with activities similar to Δ9-THC, including sedation, hypothermia, intestinal immobility, antinociception, analgesia, catalepsy, anti-emesis, and appetite stimulation.
There are at least three CB1 modulators characterized as inverse agonists/antagonists, ACOMPLIA (rimonabant, N-(1-piperidinyl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide, SR141716A), and 3-(4-chlorophenyl-N′-(4-chlorophenyl)sulfonyl-N-methyl-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamide (SLV-319), and taranabant, N-[(1S,2S)-3-(4-Chlorophenyl)-2-(3-cyanophenyl)-1-methylpropyl]-2-methyl-2-[[5-(trifluoromethyl)-2-pyridinyl]oxy]propanamide, in clinical development for treatment of eating disorders and/or smoking cessation at this time. There still remains a need for potent low molecular weight CB1 modulators that have pharmacokinetic and pharmacodynamic properties suitable for use as human pharmaceuticals.
Naphthyridone CB1 antagonists/inverse agonists are described in Debenham, et al., Bioorg. Med. Chem. Lett. 16: 681-685 (2006) and in WO 05/047285. Pyranopyridine derivatives are described in the following publications: EP 895994, WO 98/09969, WO 99/03859, WO 01/98306, WO 03/032897, WO 05/000250, WO 05/042697, and WO 06/045096.